Hands free car kit not powering up
 

A couple of weeks ago I bought a Sony Ericssson car kit from someone I
know.
First time I connected it up it worked for 10 minutes then when I turned the
car off and restarted it - nothing.

Thinking I might have pulled a wire loose somehow I removed the whole thing
and retested it and it's been refusing to play nicely ever since.

To power it , there are three wires - Black for earth - Red for permanent
12v and Blue for ignition sense that needs to be connected to a switched 12v
supply.

I reconnected the power wires to the fuse box (once fuse for switched 12v
and another for permanent 12v plus a handy earth) and checked that I was
getting the correct voltages at the connector where it goes into the car
kit.

Plugged it together , switched on the ignition and nothing happened - no
signs of life. Rechecked everything - definitely getting 12v at the
connector where it goes into the car kit but it won't work.

I removed it all as I'd run out of time and then tried again a couple of
days later with the same results. Thinking this was very odd I got my
multimeter out again and measured the volatage that I was getting at the
fuse with it connected to the car kit , and with the ignition off I was
getting 12v. If I turned the ignition on so that the ingition sense has a
12v feed but didn't start the engine , the voltage on both switched and
permanent 12v lines dropped to just 5v. When I started the engine the
voltage went back up to 12v and everything started working. I've fitted a
fair few stereos in the past and never seen anything like this before - I
can't understand why the voltage should drop that much.

I didn't have time to finish off so once again I disconnected everything and
I've just come back to look at it today. I've reconnected to the fusebox and
checked that I have the correct voltages where the cable plugs into the car
kit - all good.
This is wired exactly as it was last time , but now it won't power up at all
with the engine running or not. Thinking I may be going mad I've connected
the permanent and switched 12v wires directly to the 12v feed going into the
back of the fusebox - nothing. I definitely have the power going into it but
there's no life.

That would suggest that the car kit is faulty , but just wanting to confirm
things I popped the bonnet and connected it directly to the battery and it
works just fine.
Back to the fusebox - no life , back to the battery direct - working.

Now this is a total mystery to me. It seems to vary from week to week the
situations in which it will and won't power up and I'm checking all the
connections with a multimeter and it *is* getting power. Why should it be
happy with 12v in one place and not in another?

--
Alex

"I laugh in the face of danger. Then I hide until it goes away"

www.drzoidberg.co.uk www.ebayfaq.co.uk

Hands free car kit not powering up
 

Dr Zoidberg wrote:

Now this is a total mystery to me. It seems to vary from week to week the
situations in which it will and won't power up and I'm checking all the
connections with a multimeter and it *is* getting power. Why should it be
happy with 12v in one place and not in another?

It's that dodgy Czech build quality.

Should have bought a proper VW rather than a cheap Commie copy ;-)
--
SteveH 'You're not a real petrolhead unless you've owned an Alfa Romeo'
www.italiancar.co.uk - Honda VFR800 - Hongdou GY200 - Alfa 75 TSpark
Alfa 156 TSpark - B6 Passat 2.0TDI SE - COSOC KOTL
BOTAFOT #87 - BOTAFOF #18 - MRO # - UKRMSBC #7 - Apostle #2 - YTC #

Hands free car kit not powering up
 

Has it got a decent earth?

Hands free car kit not powering up
 

Ged wrote:
Has it got a decent earth?

Yes.
--
Alex

"I laugh in the face of danger. Then I hide until it goes away"

www.drzoidberg.co.uk www.ebayfaq.co.uk

Hands free car kit not powering up
 

On Aug 11, 4:30 pm, "Dr Zoidberg"
wrote:
Ged wrote:
Has it got a decent earth?

Yes.
--
Alex

"I laugh in the face of danger. Then I hide until it goes away"

www.drzoidberg.co.ukwww.ebayfaq.co.uk

What year is the vehicle? If its a newer model it might have CAN/VAN/
Multiplex wiring. Some ignition feeds will drop out and do funny
things under very little current draw.

Hands free car kit not powering up
 

Ged wrote:
On Aug 11, 4:30 pm, "Dr Zoidberg"
wrote:
Ged wrote:
Has it got a decent earth?

Yes.
--
Alex

"I laugh in the face of danger. Then I hide until it goes away"

www.drzoidberg.co.ukwww.ebayfaq.co.uk

What year is the vehicle? If its a newer model it might have CAN/VAN/
Multiplex wiring. Some ignition feeds will drop out and do funny
things under very little current draw.

It's an 06 octavia and it does have CAN-Bus wiring
--
Alex

"I laugh in the face of danger. Then I hide until it goes away"

www.drzoidberg.co.uk www.ebayfaq.co.uk

Hands free car kit not powering up
 

It's an 06 octavia and it does have CAN-Bus wiring
--
Alex

"I laugh in the face of danger. Then I hide until it goes away"

www.drzoidberg.co.ukwww.ebayfaq.co.uk

Are you using the ignition feed at the head unit? If you are I would
probably try running a feed from the barrel or lighter socket (if its
12v ign), pick a nice think wire. The ones at the head unit and other
locations are probably linked into the CAN bus stuff. I don't really
understand CAN bus but I know it does some funky stuff when you try
tapping anything onto it, any current draw can cause problems.

Hands free car kit not powering up
 

12v ign), pick a nice think wire. The ones at the head unit and other


.....not sure what a think wire is...probably best to try a thick
wi)

Hands free car kit not powering up
 

Ged wrote:
It's an 06 octavia and it does have CAN-Bus wiring
--
Alex

"I laugh in the face of danger. Then I hide until it goes away"

www.drzoidberg.co.ukwww.ebayfaq.co.uk

Are you using the ignition feed at the head unit?

Nope , into the fuse box onto a couple of spare terminals
--
Alex

"I laugh in the face of danger. Then I hide until it goes away"

www.drzoidberg.co.uk www.ebayfaq.co.uk

Hands free car kit not powering up
 

Nope , into the fuse box onto a couple of spare terminals
--
Alex

"I laugh in the face of danger. Then I hide until it goes away"

www.drzoidberg.co.ukwww.ebayfaq.co.uk

Hmmm, I would try going onto the back of the barrel or lighter.....it
would rule out any problems on the ignition at least.